The individual golf club heads in a set typically increase progressively in strike face surface area and weight as the clubs progress from the long irons to the short irons. Therefore, the club heads of the long irons have a smaller strike face surface area than the short irons and are typically more difficult for the average golfer to hit consistently well. For conventional club heads, this arises at least in part due to the smaller sweet spot of the corresponding smaller strike face.
To help the average golfer consistently hit the sweet spot of a club head, many golf clubs are available having heads with so-called cavity back designs with increased perimeter weighting. Another trend has been to simply increase the overall size of the club heads, especially in the long irons. Each of these features will increase the size of the sweet spot and therefore make it more likely that a shot hit slightly off the center of gravity of the club head still makes contact with the sweet spot and flies farther and straighter as a result. A challenge for the club designer when maximizing the size of the club head is desired, concerns maintaining a desirable and effective overall weight of the club. For example, if the club head of a three iron is increased in size and weight, the club may become difficult for the average golfer to properly swing.
In recent years, the importance of acoustics and vibration characteristics of golf clubs has come to the fore, because both vibration and sound are determinative in the “feel” of clubs due to the direct sensation of touch and the psycho-acoustic feedback associated with the sound. Most golfers prefer that golf clubs minimize levels of shock, vibration, and airborne noise. Shock and vibration are particularly important in determining performance and tactile sensation, while vibration and airborne noise are critical for impact and psycho-acoustic feedback to the golfer. For the average golfer, a significant sting (structure-borne vibration) on the hands frequently results from an off center (away from the “sweet spot”) impact of the club head with the golf ball. Various types of vibration damping and/or acoustic attenuating inserts have been incorporated into club heads to absorb these impact vibrations and audible sounds. However, there is still a need for improvements in weight redistribution as well as vibration damping and/or acoustic attenuation in golf club heads, and especially in iron type club heads.